A:AnswerIf you're just taking pictures, an SD card should be just fine. It's only when you get into large video sizes that a CFexpress card becomes useful. You can set your image file to Jpeg or Raw and transfer them to your computer with the SD card (as long as you have an SD card reader).
A:AnswerYou don't have to have a CFexpress card to run this camera, however if you put only SD card you are not going to have all that high quality resolution video features. SD cards have speed limitations and you need faster cards like CFexpress type B cards to record 6k and 7k videos (and use pre-continues shooting). This camera has two card slots which 1 CFexpress type B and 1 SD card. You can put any of them alone or both at the same time. However if you want the highest performance from this camera you need to put at least 1 CFExpress card. I recommend minimum 256gb or higher storage ones.